Yupp, dump the one with the problems. That will solve it, for the owner anyway.
Three young dogs, too bad there wasn't any planning involved, and the dogs are the ones that will suffer.
It is probably better to rehome the troublemaker soon. If he keeps him, then he will probably have drop three senior dogs at the shelter in quick succession, when they start being troublesome with their vet bills.
If people want to keep multiple young dogs, they have to be a leader, and be prepared to train them, and manage them. Usually male/female is fine, and usually male/male is fine, but male/male/female (spayed or not), or female/female can be very tricky.
I am not sure how you can help your friend. If he has asked for advice, then I think maybe the best thing to do is to point him to training classes, NILIF to improve his leadership, discuss managing the dogs better, and maybe neutering both boys. It usually won't help behavioral issues, but it can take some of the male-male crap because they will now not be producing all that testosterone.
Jenna, RN CGC & Babs, CD RA CGC HIC
Heidi, RA CGC
SG3 Odessa, SchH1, Kkl1, AD
Ninja, RN CGC & Milla, RN CGC
Joy, Star Puppy, RN CGC
Dolly CGC & Bear CGC